During a party, Spike reminds an irate Twilight that the ponies have to stay up all night in order to witness Princess Celestia raise the sun. Later, at the Ponyville pavilion, Mayor Mare holds a brief speech and introduces Princess Celestia, but she turns up missing, and Nightmare Moon appears in her place. Only at the end of the following episode does Princess Celestia reappear with the defeat of Nightmare Moon, and the sun subsequently rises.

The Summer Sun Celebration is featured again in Twilight Sparkle's flashback during The Cutie Mark Chronicles. Twilight describes it as "the most amazing, most wonderful thing" she'd ever seen, which made her want to study as much as she can about magic. The event itself takes place in Canterlot, where eight royal guards play a fanfare for Princess Celestia, who comes on stage and flies up, raising the sun behind her.

In the two-part Season 4 premiere, the Celebration is featured and mentioned. Unlike the previous Celebrations, this represents not the defeat of Nightmare Moon but the return of Princess Luna.

Overseeing Twilight Sparkle's studies

Princess Celestia refers to Twilight Sparkle as her "most faithful student" in the first episode, and Twilight is very proud of this fact. At the end of the second episode, Celestia tasks Twilight with staying in Ponyville with her friends and writing a weekly report about her studies of the "magic of friendship", which Twilight usually sends via Spike. These letters typically serve to illustrate each episode's moral for the show's viewers.

During a flashback in The Cutie Mark Chronicles, Princess Celestia witnesses Twilight's rare magical talents and takes her as a protégé. Lauren Faust has suggested that there is more to Princess Celestia than has been depicted of her in the series. Relating to the events in the flashbacks in The Cutie Mark Chronicles, Celestia sensed that Twilight Sparkle was connected to the Elements of Harmony and arranged the dragon-hatching test for her. Celestia then raised and trained Spike, and subsequently assigned him to be Twilight's assistant.[8]

Answering a letter from Twilight Sparkle.

Celestia has been present during an episode in a few cases, allowing for Twilight Sparkle or another pony to deliver the report to her in person. She arrives for a scheduled royal visit in Swarm of the Century, and meets the six main ponies outside of Ponyville where Twilight makes her report. She attends the Running of the Leaves in Fall Weather Friends as "Fall is one of [her] favorite seasons", and Twilight makes a brief report about friendship being more important than a competition. She also attends the Best Young Flyer competition in Sonic Rainboom, where Rarity delivers the report to her directly. She is present for a royal visit in A Bird in the Hoof, so she hears Twilight Sparkle's intended report from Fluttershy.

Celestia makes a surprise cameo at the end of Feeling Pinkie Keen, dropping out of the sky to grab Spike's letter and then taking off just as quickly, confirming another one of Pinkie Pie's twitchy tail predictions.

Celestia is asked to come to Ponyville by Spike in Lesson Zero, after Twilight, fearing that being unable to send a friendship report will have dire consequences, enchants a doll, causing all of Ponyville to fight over it. Celestia arrives and undoes the spell, then sternly asks Twilight to meet her at the library. Despite Twilight's fears, Celestia does not reprimand her, telling her that she should only send a friendship report if she learns a lesson. She also decrees that Twilight's friends may also send her friendship reports.

Celestia makes a brief appearance in Sweet and Elite, showing Rarity to the room she will stay in while visiting Canterlot. She also displays awkwardness at Rarity fawning over her in thanks. At the end of the episode, she hears Rarity's friendship report. She next appears in It's About Time, passing by the "Star Swirl the Bearded" wing of the Canterlot library. She shows no signs of objection to seeing Twilight who had made an elaborate show of sneaking in, and compliments Twilight for her new hairstyle.

Celestia disappointed at Twilight.

Celestia presides over the wedding of Princess Cadance and Shining Armor in A Canterlot Wedding - Part 1 and Part 2, and monitors an anonymous threat that was made against Canterlot. The threat turns out to be an invasion by the changelings and their queen, who was already in Canterlot impersonating Princess Cadance. However, through most of the two-part episode, no one except Twilight suspects there's something wrong with Cadance. When Twilight brands the fake Cadance as "evil" at the wedding rehearsal, Celestia is greatly disappointed by her actions and agrees with Shining Armor's suggestion for Twilight not to bother coming to the wedding. Celestia sternly tells Twilight, "You have a lot to think about," before walking out on her with the others. However, after the exposure and defeat of Queen Chrysalis and the wedding ceremony, Celestia commends Twilight for persisting in the face of doubt and following her instincts in bringing Princess Cadance back, reaffirming their good relationship.

Showing Twilight how she succeeded her task of creating new magic in Magical Mystery Cure

In Magical Mystery Cure, Princess Celestia appears in a starry realm with Twilight Sparkle, revealing that she had sent Twilight the spell book of Star Swirl the Bearded as a test, which Twilight had passed by creating new magic. Just as Celestia starts singing, dozens of images float by, depicting Twilight's lessons and everyday studies, and she tells her about how it is time for Twilight to fulfill her destiny. Twilight, now having been transformed into an Alicorn, frets that she will no longer be Celestia's student. Celestia reassures her that she will still be her student but in "a different way" - that Celestia and the other princesses will also be learning from Twilight now, as well. She then arranges a coronation ceremony for Twilight, to crown her as Equestria's newest princess.

Personality

Celestia's first act of wisdom inFriendship is Magic, part 2.

Princess Celestia acts as a mentor to Twilight Sparkle. She often does not directly state her goals but rather gives the advice to help her students find the answers they need. For example, she wrote a letter prompting Twilight to make friends in Friendship is Magic, part 1 when her goal was for Twilight Sparkle to find theElements of Harmony.

"I told you that you needed to make some friends, nothing more..."

— Celestia to Twilight Sparkle

Despite being royalty, she often encourages her subjects to relax with jokes and gentle questions. She also shows great patience with any inappropriate behavior towards her, as seen when Pinkie Pie snatches a cupcake from her at a party in A Bird in the Hoof.

Celestia's mischief with tea cup refills.

Princess Celestia displays a fun-loving side when she chuckles at the bottle of disappearing ink sent to her by Twilight in Griffon the Brush Off. In A Bird in the Hoof, while sipping from a constantly refilled cup of tea, she pretends to sip from her already full cup, causing Mr. and Mrs. Cake to overfill it. She watches with a smile on her face when Pinkie Pie devours one of the her cupcakes, while Mrs. Cake gasps and drags Pinkie away. Celestia tells Twilight and her friends in The Best Night Ever, after they ruin the Grand Galloping Gala, that she always found the Gala awful and she was hoping they would liven it up.

While kindhearted and slow to anger, Celestia's patience does have its limits. When faced against the threat of Discord's return in The Return of Harmony Part 1, Celestia wastes no time in demanding that Discord return the stolen Elements of Harmony. Also, in Lesson Zero, when Spike makes her aware that Twilight inadvertently unleashed mass chaos onto Ponyville in her obsessive attempts to find a friendship report to send to the Princess, Celestia personally intervenes to undo Twilight's out-of-control spell. She sternly orders her student to a private meeting to discuss her actions but remains understanding, and at the insistence of Twilight's friends she agrees not to punish Twilight, instead asking them all to send her friendship reports only when the lessons make themselves apparent to them. In A Canterlot Wedding - Part 1, after Twilight accuses imposter Cadance of being evil with no evidence to back her claims, Princess Celestia, along with the others, makes clear her deep disappointment in her student and walks out on Twilight after Shining Armor and the other ponies. But in A Canterlot Wedding - Part 2, while displaying righteous rage to the newly exposed Queen Chrysalis, she eventually commends Twilight for her instincts that told her the imposter Cadance was evil.

In Ponyville Confidential, the Cutie Mark Crusaders manage to get a hold of a photo depicting her eating cake in an unladylike manner for their Foal Free Press gossip column titled "Celestia: Just like us." At the end of MMMystery on the Friendship Express, she admires the cake made by the combined efforts of the bakers and overlooks Pinkie's attempts to gain her attention.

Celestia can also be very forgiving. She does not admonish Fluttershy for taking Philomena without asking in A Bird in the Hoof. As mentioned above, she does not punish Twilight for the chaos she caused in Lesson Zero. In Keep Calm and Flutter On, she firmly believed that Discord could be redeemed, in spite of the trouble he had caused in the past.

She mentions that Fall is one of her favorite seasons in Fall Weather Friends while at Ponyville to celebrate the Running of the Leaves.

Magic

Celestia says that only she can open the room where the Elements of Harmony are stored.

The legend narrated in the first episode tells that Celestia raises the sun, and that she had raised the moon and stars in her sister's absence. A display of Celestia raising the sun is depicted in The Cutie Mark Chronicles, and the sunrise coincides with Princess Celestia's return in Friendship is Magic, part 2. Princess Celestia's cutie mark is a stylized sun, which matches her responsibility of raising the sun. Celestia is said to have wielded the Elements of Harmony on two occasions. The first is in the legend narrated in the show's first episode, which says that "the elder sister" [Celestia] used the elements to banish Nightmare Moon. The second is in The Return of Harmony Part 1, where Celestia says that she and her sister discovered the Elements of Harmony and used them to defeat Discord. In the same episode, Celestia further explains to Twilight and her friends that she and Luna are no longer connected to the Elements, and that Twilight and her friends have to face Discord with the Elements now. Both of the confrontations and using the Elements against Discord and Nightmare Moon are fully explained in minor detail in Princess Twilight Sparkle - Part 1 and Princess Twilight Sparkle - Part 2.

Other than raising the sun and wielding the Elements of Harmony, Princess Celestia displays telekinesis in various episodes and in the show's opening sequence. Other instances of her using magic are in The Cutie Mark Chronicles, where she stops Twilight Sparkle's wild magic burst, and in Lesson Zero, where she dispels the "want it, need it" spell from a massive amount of affected ponies at once.

Princess Celestia vs. Queen Chrysalis

Celestia finds herself unable to overpower the magic of Queen Chrysalis in A Canterlot Wedding - Part 2. Celestia attacks Chrysalis with a beam from her horn, and Chrysalis retaliates with a beam of her own, which repulses Celestia's beam. However, this instance of Celestia being overpowered was because Chrysalis's own magic had been augmented by her feeding on Shining Armor's love for Princess Cadance.

In The Crystal Empire - Part 1, both Celestia and Twilight use some magic that surrounds their horn with black fog and makes their irises glow red and their eyes glow green and emit a purple trail, much like King Sombra's usual appearance. The magic causes black crystals to grow from the ground, again in the same fashion as King Sombra's magic. Celestia says this demonstrates what would happen if hatred and fear took hold of the Crystal Empire. When Twilight uses this magic, she mentions to Spike that she learned it from Celestia. In addition, Celestia used her magic alongside Luna to turn King Sombra to shadow and banish him within the ice of the arctic north.

In Twilight's Kingdom - Part 2, Princess Celestia performs a magic transferring ritual with Princess Luna and Princess Cadance. When completed, Celestia loses her sun cutie mark and is left weak and fatigued, but she regains it alongside her magic following Twilight and her friends' victory over Lord Tirek and the return of all the stolen magic.